The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
The present invention generally relates to wellsite surface equipment such as wireline surface equipment and the like. In particular, the invention is directed to an assembly, a system, and a method for measuring a tension in a cable.
During a typical wireline operation a tool string is moved up and down in a well using a winch. Specifically, the tool string is attached to a cable, whereby the cable is spooled/unspooled on a drum. In this context, it is critical to monitor a tension in the cable to prevent operational pitfalls such as cable breaks (e.g. tool string stuck into the well), cable slacking (e.g. not enough cable tension), and the like.
Currently, cable tension is measured using a Cable Mounted Tension Device (CMTD), wherein the cable is trapped between three wheels and a shaft is deformed proportionally to the cable tension. For monitoring a tension in the cable, the shaft deformation is sensed by a strain gauge.
In certain instances, a conventional strain gauge has shown some reliability issues and the wheels of the CMTD can damage the winch cable (under high tension the CMTD could even break the cable).
More accurate assemblies, systems, and methods are needed for measuring the tension of a cable, without the use of a CMTD. It also remains desirable to provide improvements in wellsite surface equipment in efficiency, flexibility, reliability, and maintainability.